Four apps, one home screen, all claiming to be your AI assistant. Which chatbot apps are actually worth the storage? This AI chatbot app download guide answers app by app. - The ChatGPT app: the safe first download. The most features, the biggest ecosystem, the most polished mobile experience. - The Claude app: the writer's pick. Clean interface, strong long-document handling. - The Gemini app: makes sense if your life runs on Google apps, and it is already sitting on many Android phones. - The Copilot app: the sleeper for Microsoft households. All four are free, so check storage sizes and permissions on each store listing rather than trusting a blog post. Before you download all four, name your primary job: daily writing, everything-plus-ecosystem, Google-centric, or Microsoft-centric. Download your best guess first, use it a week, then add one challenger. StackAudit recommends the optimal 3 to 5 tool AI stack for your profession with pricing and setup guides for $4.99 one-time unlock.